Forming Storms

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Forming Storms
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Targets

• Describe the different methods of creating
  thunderstorms
• Explain how a thunderstorm develops in stages

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Forming Storms

• Stable air air that doesnt rise cold dense
• Pockets of air warmer (less dense) than
  surrounding air are unstable.
• Unstable air reaches dew point makes
  cumulonimbus clouds

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Forming Storms

• Air-mass thunderstorms occur from uneven heating
  of air
• 2 types of air-mass thunderstorms
• Orographic air pushed over mountains
• Sea-breeze thunderstorms along coasts
• Why do most air-mass thunderstorms occur in
  mid-afternoon?

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Forming Storms

• At the dew point, water condenses releases
  latent heat.
• Latent heat warms the cloud causes it to keep
  rising.

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Sea-breeze Thunderstorm
Unstable Air
Stable Air
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Forming Storms

• Frontal Thunderstorms warm air is forced up
  over cold air at cold front.
• Can be at any time of day.

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Storm Stages

• Stages of Storms
• Cumulus stage
• air rises vertically creating updrafts
• Condensation creates droplets, rain releases
  latent heat

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Storm Stages

• 2. Mature stage
• Rain falls cools the air around it
• Cooled air is dense falls to create downdrafts
• Up downdrafts create convection cells

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Storm Stages

• 3. Dissipation Stage
• Convection stops when warm, moist air runs out
• Downdrafts cool the land around the storm end
  the storm

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Supercells severe thunderstorms with large
temperature differencesCan last hours updrafts
up to 240 km/hr
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Severe Weather

• Downbursts violent downdrafts (over 160 km/hr)
  focused in one area
• Hail ice stones
• Forms when ice pellets high in the cloud fall
  through water drops low in the cloud.
• Water drops freeze on the pellets then updrafts
  push the ice back to the top.

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